What is the operating mechanism of include and require in PHP?

When learning Zend, you can see the following code: {code ...} I also made some attempts: var_dump (require & #039; test. php & #039;) 1. if no return statement exists, the output is: {code ...} 2. if the return statement is used, enter the return data: {code ...} may I ask PHP... the following code is displayed during Zend learning:

$config = new Zend_Config(require 'config.php');

I also made some attempts:
Var_dump (require 'test. php ')
1. If there is no return statement, the output is:

int(1)

2. If the return statement is used, the input is the return data:

...

What are the require and include mechanisms of PHP?
PS: although the PHP source code has been downloaded, I cannot find a clue at the moment.

Update
One test. php output. php

// output.phpoutput(require 'test.php');// or output(include 'test.php');function output($test) {    var_dump($test);}

Scenario 1

// test.php 1return 123;

// output 1int(123)

Scenario 2

// test.php 2echo 123;

// output 2123int(1)

Case 3

// test.php 3echo 123;die;

// output 3123

Reply content:

The following code is displayed during Zend learning:

$config = new Zend_Config(require 'config.php');

I also made some attempts:
Var_dump (require 'test. php ')
1. If there is no return statement, the output is:

int(1)

2. If the return statement is used, the input is the return data:

...

What are the require and include mechanisms of PHP?
PS: although the PHP source code has been downloaded, I cannot find a clue at the moment.

Update
One test. php output. php

// output.phpoutput(require 'test.php');// or output(include 'test.php');function output($test) {    var_dump($test);}

Scenario 1

// test.php 1return 123;

// output 1int(123)

Scenario 2

// test.php 2echo 123;

// output 2123int(1)

Case 3

// test.php 3echo 123;die;

// output 3123

According to the official explanation provided by php, the difference between require and include is that a fatal error is thrown when require encounters an error, while include only throws warning.

Require () is identical to include () failed t upon failure it will also produce a fatal E_COMPILE_ERROR level error. in other words, it will halt the script whereas include () only emits a warning (E_WARNING) which allows the script to continue.
See the include () documentation for how this works.

Their principle is: parse the file to be included according to HTML, and replace the output content with the position of the include statement.

There is a Laruence article here for reference to http://www.laruence.com/2010/05/04/14...